A176650 Numbers k such that nonnegative non-semiprime(k)+3 = nonnegative non-semiprime(k+3).

1, 11, 12, 18, 19, 20, 26, 27, 28, 47, 53, 63, 64, 65, 66, 67, 68, 69, 73, 83, 84, 91, 92, 93, 98, 99, 100, 101, 102, 109, 115, 116, 117, 118, 122, 128, 129, 130, 134, 135, 136, 148, 152, 153, 154, 155, 156, 161, 162, 163, 164, 165, 166, 174, 183, 184, 185, 192, 193

Offset: 1

Author

Juri-Stepan Gerasimov, Apr 22 2010

Keywords

• nonn

Comments

Where nonnegative non-semiprime numbers are zero together with A100959 (i.e., 0, 1, 2, 3, 5, 7, 8, 11, 12, 13, 16, 17, 18, 19, 20, 23, 24, 27, 28, 29, 30, ...).

Examples

			1 is a term because nonnegative non-semiprime(1)+3 = 3 = nonnegative non-semiprime(1+3).
		

Links

• Jinyuan Wang, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A100959 (non-semiprimes).

Programs

Maple

A100959 := proc(n) option remember; if n = 1 then 1; else for a from procname(n-1)+1 do if numtheory[bigomega](a) <> 2 then return a; end if; end do end if; end proc:
nnnspr := proc(n) if n = 1 then 0; else A100959(n-1) ; end if; end proc:
isA176650 := proc(n) nnnspr(n) + 3 = nnnspr(n+3) ; end proc:
for n from 1 to 1200 do if isA176650(n) then printf("%d,",n) ; end if; end do:
# R. J. Mathar, Apr 26 2010

Mathematica

Join[{1},Flatten[With[{c=Select[Range[0,300],PrimeOmega[#]!=2&]},Position[ Partition [c,4,1],?(#[[1]]+3==#[[4]]&),1,Heads->False]]]+1] (* _Harvey P. Dale, Oct 15 2022 *)

Extensions

Entries checked by R. J. Mathar, Apr 26 2010